Buried low-resistance metal word lines for cross-point variable-resistance material memories

ABSTRACT

Variable-resistance material memories include a buried salicide word line disposed below a diode. Variable-resistance material memories include a metal spacer spaced apart and next to the diode. Processes include the formation of one of the buried salicide word line and the metal spacer. Devices include the variable-resistance material memories and one of the buried salicided word line and the spacer word line.

PRIORITY APPLICATION

This application is a divisional of U.S. application Ser. No.14/844,747, filed Sep. 3, 2015, which is a divisional of U.S.application Ser. No. 11/857,682, filed Sep. 19, 2007, now issued as U.S.Pat. No. 9,129,845, each of which is incorporated herein by reference inits entirety.

TECHNICAL FIELD

This disclosure relates generally to variable-resistance materialrandom-access memories.

BACKGROUND

Variable-resistance material memory structures often rely upon heavilydoped semiconductive leads that serve as the word line in a cross-pointvariable-resistance material random-access memory. A significantparasitic resistance drop may occur in such a word line due to theprogramming current used in a variable-resistance material random-accessmemory. Backend metal line strapping therefore can be applied to reduceword line resistance. This metal line strapping can also cause furthercomplications in memory cell size and in processing complexity.

What are needed are methods to form better structures that can addressthese challenges. Also needed are improved variable-resistance materialrandom-access memory structures that can also address these challenges.

BRIEF DESCRIPTION OF THE DRAWINGS

Disclosed embodiments are addressed by the present disclosure and willbe understood by reading and studying the following specification, ofwhich the figures are a part.

FIGS. 1a-1h and 1j-1k show cross-section elevations of a semiconductordevice during processing according to an embodiment;

FIG. 2 shows a perspective elevation of a variable-resistance materialmemory device according to an embodiment;

FIG. 3 shows a cross-section elevation of a variable-resistance materialmemory device according to an embodiment;

FIG. 4 shows a process flow for fabricating the structures depicted inFIGS. 1a through 3 according to an embodiment;

FIGS. 5a-5h and 5j-5k show cross-section elevations of a semiconductordevice during processing according to an embodiment;

FIG. 6 shows a process flow for fabricating the structures depicted inFIGS. 5a through 5k according to an embodiment;

FIGS. 7a to 7f show cross-section elevations of a semiconductor deviceduring processing according to an embodiment:

FIG. 8 shows a process flow for fabricating the structures depicted inFIGS. 7a through 7f according to an embodiment;

FIGS. 9a to 9f show cross-section elevations of a semiconductor deviceduring processing according to an embodiment;

FIG. 10 shows a process flow for fabricating the structures depicted inFIGS. 7a through 7f according to an embodiment;

FIG. 11 shows a block diagram of an electronic device according to anembodiment; and

FIG. 12 shows a block diagram of an electronic device according to anembodiment.

DETAILED DESCRIPTION

The embodiments of a device, an apparatus, or an article describedherein can be manufactured, used, or shipped in a number of positionsand orientations. A variable-resistance material memory device mayinclude a material such as an alloy. A variable-resistance materialmemory device may include a material such as a quasi-metal composition.A variable-resistance material memory device may include a material suchas metal oxides. A variable-resistance material memory device mayinclude a material such as chalcogenides. These several materials can bevery diverse in quality and performance.

FIG. 1a shows a cross-section elevation of a semiconductor device 100during processing according to an embodiment. A semiconductive lowersubstrate 110 has been formed below a semiconductive upper substrate112. In an embodiment, the semiconductive lower substrate 110 is P−doped in comparison to the semiconductive upper substrate 112 that is N+doped.

A dielectric film 114 such as silicon dioxide is formed upon the uppersurface 116 of the semiconductive upper substrate 112. A first hard mask118 is disposed above the dielectric film 114, and the hard mask 118 andthe dielectric film 114 have been patterned to expose the upper surface116. The first hard mask includes a vertically exposed surface 124. Inan embodiment, the first hard mask 118 is a nitride material likesilicon nitride such as Si₃N₄.

FIG. 1b shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1a after further processing according to an embodiment.The semiconductor device 101 has been etched through the upper surface116 (FIG. 1a ) to form a first recess 120 including a first recessbottom 122. The first hard mask 118 also exhibits the vertically exposedsurface 124 that facilitates a directional etch into the semiconductiveupper substrate 112.

FIG. 1c shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1b after further processing according to an embodiment.The semiconductor device 102 has been processed to form a first recess120 including a first recess bottom 122. A first spacer 126 has beenformed by blanket deposition and a spacer etch. In an embodiment, thefirst spacer 126 and the first hard mask 118 are nitride materials, andthe spacer etch, although it is selective to etching nitride materials,removes the nitride material upon the first recess bottom 122 as well asupon the vertically exposed surfaces 124 of the first hard mask 118.Consequently in an embodiment as depicted in FIG. 1c , the first hardmask 118 (FIG. 1b ) may be slightly height-reduced to become the firsthard mask 119.

FIG. 1d shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1c after further processing according to an embodiment.The semiconductor device 103 has been etched through the first recessbottom 122 (FIG. 1c ) to form a second recess 128, a pillar 129 of someof the semiconductive upper substrate 112, and a second recess bottom130 in some of the semiconductive upper substrate 112.

FIG. 1e shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1d after further processing according to an embodiment.The semiconductor device 104 has been blanket deposited with a firstmetal 132. The first metal 132 is used to form a silicide in thesemiconductive upper substrate 112.

FIG. 1f shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1e after further processing according to an embodiment.The semiconductor device 105 has been processed under conditions tocause salicidation (self-aligned silicidation) of the first metal 132into the semiconductive upper substrate 112 including into the pillar129 that is part of the semiconductive upper substrate 112. A salicidestructure 134 is formed by this process. In an embodiment, the firstmetal 132 is cobalt (Co), and the process has allowed the salicidestructure 134 to form as cobalt silicide (CoSi₂) material. Further, boththe sidewalls of the second recess 128 and the second recess bottom 130have been consumed and transformed into the salicide structure 134.After salicidation, any excess first metal 132 is removed with astripping procedure that is selective to leaving the salicide structure134 as well as the first hard mask 119 and the first spacer 126.

FIG. 1g shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1f after further processing according to an embodiment.The semiconductor device 106 has been processed with a shallow-trenchisolation (STI) 136. Before formation of the STI 136, a third etch hasbeen carried out that penetrates the salicide structure 134 (FIG. 1f )to form a buried salicide word line 135 in the pillar 129. The thirdetch further penetrates the semiconductive upper substrate 112, and thatmay further penetrate into the semiconductive lower substrate 110.Consequently, a given STI 136 effectively isolates neighboring buriedsalicide word lines 135. The STI 136 may be processed by a blanketdeposition, followed by an etchback or a chemical-mechanical polishingthat stops on the first hard mask 119.

FIG. 1h shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1g after further processing according to an embodiment.The semiconductor device 107 has been processed with a fourth etch thathas penetrated the first hard mask 119 and that exposes the pillar 129at a pillar upper surface 138. The fourth etch includes an etch recipethat is selective to leaving the semiconductive material of thesemiconductive upper substrate 112, particularly at the pillar 129.

FIG. 1j shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1h after further processing according to an embodiment.The semiconductor device 108 has been processed by growing an epitaxialfirst film 140 upon the pillar 129 at the pillar upper surface 138 (FIG.1h ). In an embodiment where the pillar 129 is an N+ silicon, theepitaxial first film 140 is an N− silicon. In an embodiment, formationof the epitaxial first film 140 is carried out by in situ N− dopingduring epitaxial growth In an embodiment, formation of the epitaxialfirst film 140 is carried out by epitaxial growth, followed by light N−doping thereof. In an embodiment, the epitaxial first film 140 fills thevia 138 (FIG. 1h ) and then is planarized by etchback or by polishing.In an embodiment, a counter-doped second film 142 is formed by P+implantation into the surface of the epitaxial first film 140 bycounter-doping.

After formation of the epitaxial first film 140, a diode 140, 142 isconfigured In an embodiment, the diode 140, 142 is formed by growing anepitaxial second film 142 above and on the epitaxial first film 140.

In an embodiment where the epitaxial first film 140 is an N− silicon,the epitaxial second film 142 is a P+ silicon. In an embodiment,formation of the epitaxial second film 142 is carried out by in situ P+doping during epitaxial growth. In an embodiment, formation of theepitaxial second film 142 is carried out by epitaxial growth, followedby heavy P+ doping thereof.

Hereinafter, both the epitaxial second film 142 and counter-doped secondfilm 142 will be referred to as the second film 142 unless otherwiseexplicitly stated.

FIG. 1k shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1j after further processing according to an embodiment.The semiconductor device 109 has been processed to form a silicidecontact 144. After formation of the diode 140, 142 (FIG. 1j ),silicidation of a portion of the second film 142 is carried out. In anembodiment, a cobalt film is deposited over the second film 142 andthermal conversion of a portion of the P+ second film 142 is carriedout. Consequently, the diode structure is altered and takes the form ofthe epitaxial first film 140, and an altered second film 142.

Salicidation has formed the silicide contact 144 above the second film142.

Further processing includes the formation of a bottom electrode 146 in adielectric film 148 such as a silicon oxide film or a silicon nitridefilm. The bottom electrode 146 is depicted as making contact with thesilicide contact 144, and is illustrated as an open-ended cylinder.Other types of bottom electrodes can be implemented such as plug bottomelectrodes, liner electrodes, and others.

FIG. 2 shows a perspective elevation of a phase-change memory device 200according to an embodiment. A pillar 229 that has been formed from asemiconductive upper substrate 212, which rests upon semiconductivelower substrate 210. A buried salicide word line 235 is disposed in thepillar 229, and a diode 240, 242 made of two different semiconductivematerials is disposed upon the pillar 229. A silicide contact 244 isdisposed upon the second film 242 that is part of the diode 240, 242. Abottom electrode 246 is disposed in a dielectric film 248 such as asilicon oxide film or a silicon nitride film. The bottom electrode 246is depicted as making contact with the silicide contact 244 and isillustrated as an open-ended cylinder.

A word line strap 250 is depicted as penetrating the pillar 229.Although not depicted, the pillar 229 is isolated from adjacent andspaced-apart pillars by STI structures.

FIG. 3 shows a cross-section elevation of a phase-change memory device300 according to an embodiment. A pillar 329 that has been formed from asemiconductive upper substrate 312 rests upon semiconductive lowersubstrate 310. In an embodiment, the pillar is made of an N+ dopedsilicon, and the semiconductive lower substrate 314 is made of a P−doped silicon.

A buried salicide word line 335 is disposed in the pillar 329, and adiode 340, 342 made of two different semiconductive materials isdisposed upon the pillar 329. In an embodiment, the diode 340, 342 ismade of an N− doped epitaxial first film 340, and a partially consumedP+ doped second film 342.

A silicide contact 344 is disposed upon the second film 342 that is partof the diode 340, 342. A bottom electrode 346 is disposed in adielectric film 348 such as a silicon oxide film In an embodiment, thebottom electrode 346 is a conductor such as titanium nitride, titaniumaluminum nitride, titanium nickel tin, tantalum nitride, tantalumsilicon nitride, and others. The bottom electrode 346 is depicted asmaking contact with the silicide contact 344.

The bottom electrode 346 contacts a variable-resistance material 352. Inan embodiment, variable-resistance material 352 is a phase-changematerial such as a chalcogenide material.

In an embodiment, the variable-resistance material that may be used as aphase-change random-access memory (PCRAM) cell is a gallium (Ga)containing material. Selected gallium-containing materials that may beused include GaSb, Ga—Ge—Sb, Ga—Se—Te, and others. In somegallium-containing phase-change material embodiments, the gallium ispresent in a majority amount (greater than or equal to 50 percent). Insome gallium-containing phase-change material embodiments, the galliumis present in a plurality amount (gallium being the most prevalentelement). In some embodiments, the first-listed element is present ineither a majority or plurality amount, and the subsequent-listedelements are listed by order of decreasing amounts on an elementalscale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is a germanium (Ge) containing material. Selectedgermanium-containing materials that may be used include Ge—Te, Ge—Sb—Te,Ge—Te—As, Ge—Se—Ga, Ge—In—Sb, Ge—Te—Sb—S, Ge—Te-Sn_o, Ge—Te—Sn_Au,Ge—Pd—Te—Sn, Ge—Sb—Te—Pd, Ge—Sb—Te—Co, Ge—Sb—Se—Te, Ge—Sn—Te,Ge—Te—Sn—Ni, Ge—Te—Sn—Pd, Ge—Te—Sn—Pt, and others. In somegermanium-containing phase-change material embodiments, the germanium ispresent in a majority amount (greater than or equal to 50 percent). Insome germanium-containing phase-change material embodiments, thegermanium is present in a plurality amount (germanium being the mostprevalent element). In some embodiments, the first-listed element ispresent in either a majority or plurality amount, and thesubsequent-listed elements are listed by order of decreasing amounts onan elemental scale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is an indium (In) containing material. Selectedindium-containing materials that may be used include In—Se, In—Sb,In—Sb—Te, In—Sb—Ge, In—Se—Ti—Co, In—Ag—Sb—Te, and others. In someindium-containing phase-change material embodiments, the indium ispresent in a majority amount (greater than or equal to 50 percent). Insome indium-containing phase-change material embodiments, the indium ispresent in a plurality amount (indium being the most prevalent element).In some embodiments, the first-listed element is present in either amajority or plurality amount, and the subsequent-listed elements arelisted by order of decreasing amounts on an elemental scale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is an antimony (Sb) containing material. Selectedantimony-containing materials that may be used include Sb₂Te₃, Sb—Ga,Sb—Bi—Se, Sb—Sn—Te, Sb—In—Ge, Sb—Te—Ge—S, Sb—Ge—Te—Pd, Sb—Ge—Te—Co,Sb—Te—Bi—Se, Sb—Ag—In—Te, Sb—Ge, Sb—Ge—Se—Te, Sb—Ge—Sn—Te, and others Insome antimony-containing phase-change material embodiments, the antimonyis present in a majority amount (greater than or equal to 50 percent).In some antimony-containing phase-change material embodiments, theantimony is present in a plurality amount (antimony being the mostprevalent element). In some embodiments, the first-listed element ispresent in either a majority or plurality amount, and thesubsequent-listed elements are listed by order of decreasing amounts onan elemental scale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is a tellurium (Te) containing material. Selectedtellurium-containing materials that may be used include Te—Ge, Te—Sb,Te—As, Te—Al, Te—Ge—Sb, Te—Ge—As, Te—In—Sb, Te—Sn—Se, Te—Ga—Se,Te—Sn—Sb, Te—Ge—Sb—S, Te—Ge—Sn—O, Te—Ge—Sn—Au, Te—Pd—Ge—Sn, Te—Ge—Sb—Pd,Te—Ge—Sb—Co, Te—Sb—Bi—Se, Te—Ag—In—Sb, Te—Ge-Ab-Se, Te—Ge—Sn—Sb,Te—Ge—Sn—Ni, Te—Ge—Sn—Pd, Te—Ge—Pd—Pt and others. In sometellurium-containing phase-change material embodiments, the tellurium ispresent in a majority amount (greater than or equal to 50 percent). Insome tellurium-containing phase-change material embodiments, thetellurium is present in a plurality amount (tellurium being the mostprevalent element). In some embodiments, the first-listed element ispresent in either a majority or plurality amount, and thesubsequent-listed elements are listed by order of decreasing amounts onan elemental scale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is a selenium (Se) containing material. Selectedselenium-containing materials that may be used include Se—In, Se—Te—Sn,Se—Ge—Ga, Se—Bi—Sb, Se—Ga—Te, Se—In—Ti—Co, Se—Sb—Te—Bi, Se—Ge—Sb—Te, andothers In some selenium-containing phase-change material embodiments,the selenium is present in a majority amount (greater than or equal to50 percent). In some selenium-containing phase-change materialembodiments, the selenium is present in a plurality amount (seleniumbeing the most prevalent element). In some embodiments, the first-listedelement is present in either a majority or plurality amount, and thesubsequent-listed elements are listed by order of decreasing amounts onan elemental scale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is an arsenic (As) containing material. Selectedarsenic-containing materials that may be used include As—Te, As—Te—Ge,and others. In some arsenic-containing phase-change materialembodiments, the arsenic is present in a majority amount (greater thanor equal to 50 percent). In some arsenic-containing phase-changematerial embodiments, the arsenic is present in a plurality amount(arsenic being the most prevalent element). In some embodiments, thefirst-listed element is present in either a majority or pluralityamount, and the subsequent-listed elements are listed by order ofdecreasing amounts on an elemental scale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is an aluminum (Al) containing material. Selectedaluminum-containing materials that may be used include Al—Te, Al—Se andothers. In some aluminum-containing phase-change material embodiments,the aluminum is in a majority amount.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is a tin (Sn) containing material. Selected tin-containingmaterials that may be used include Sn—Te—Se, Sn—Sb—Te, Sn—Te—Ge—O,Sn—Pd—Te—Ge, Sn—Ge—Sb—Te, Sn—Ge—Sb—Te, Sn—Ge—Te—Ni, Sn—Ge—Te—Pd,Sn—Ge—Te—Pt, and others. In some tin-containing phase-change materialembodiments, the tin is present in a majority amount (greater than orequal to 50 percent). In some tin-containing phase-change materialembodiments, the tin is present in a plurality amount (tin being themost prevalent element). In some embodiments, the first-listed elementis present in either a majority or plurality amount, and thesubsequent-listed elements are listed by order of decreasing amounts onan elemental scale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is a palladium (Pd) containing material. Selectedpalladium-containing materials that may be used include Pd—Te—Ge—Sn,Pd—Ge—Sb—Te, and others. In some palladium-containing phase-changematerial embodiments, the palladium is present in a majority amount(greater than or equal to 50 percent). In some palladium-containingphase-change material embodiments, the palladium is present in aplurality amount (palladium being the most prevalent element). In someembodiments, the first-listed element is present in either a majority orplurality amount, and the subsequent-listed elements are listed by orderof decreasing amounts on an elemental scale.

In an embodiment, the variable-resistance material that may be used as aPCRAM cell is a silver (Ag) containing material. Selectedsilver-containing materials that may be used include Ag—In—Sb—Te, andothers. In some silver-containing phase-change material embodiments, thesilver is present in a majority amount (greater than or equal to 50percent). In some silver-containing phase-change material embodiments,the silver is present in a plurality amount (silver being the mostprevalent element). In some embodiments, the first-listed element ispresent in either a majority or plurality amount, and thesubsequent-listed elements are listed by order of decreasing amounts onan elemental scale.

In an embodiment, the variable resistance material 352 may include oneof various materials used to form so-called “colossal magnetoresistivefilms” such as, for example, Pr_((1-x))Ca_(x)MnO₃ (PCMO),La_((1-x))Ca_(x)MnO₃ (LCMO), and Ba_((1-x))Sr_(x)TiO₃.

In an embodiment, the variable resistance material 352 may include abinary or ternary doped or undoped oxide material such as, for example,Al₂O₃, BaTiO₃, SrTiO₃, Nb₂O₅, SrZrO₃, TiO₂, Ta₂O₅, NiO, ZrO_(x),HfO_(x), and Cu₂O.

In an embodiment, the variable resistance material 352 may have aPerovskite structure.

In an embodiment, the variable resistance material 352 includes a dopedchalcogenide glass of the general formula A_(x)B_(y), where B isselected from sulfur (S), selenium (Se), and tellurium (Te), andmixtures thereof, and where A includes at least one element from GroupIII-A (B, Al, Ga, In, Tl), Group IV-A (C, Si, Ge, Sn, Pb), Group V-A (N,P, As, Sb, Bi), or Group VII-A (F, Cl, Br, I, At) with one or moredopants selected from noble metal and transition metal elements such as,for example, Au, Ag, Pt, Cu, Cd, In, Ru, Co, Cr, Ni, Mn, and Mo.

A word line strap 350 is depicted as penetrating the flanged part of thepillar 329. The pillar 329 is isolated from adjacent and spaced-apartpillars by STI structures 336. The STI structures 336 are depicted astapered, which form may occur under various etching processes.

In an embodiment, the variable resistance material memory device 300 isa phase-change memory device 300. The pillar 329 that has been formedfrom the semiconductive upper substrate 312, rests upon thesemiconductive lower substrate 310. In an embodiment, the pillar 329 ismade of an N+ doped silicon, and the semiconductive lower substrate 310is made of a P− doped silicon.

The buried salicide word line 335 is disposed in the pillar 329, and thediode 340, 342 is made of two different semiconductive materials. In anembodiment, the diode 340, 342 is made of an N− doped epitaxial firstfilm 340 and a partially consumed P+ doped second film 342.

The silicide contact 344 is disposed upon the second film 342 that ispart of the diode 340, 342. The bottom electrode 346 is disposed in adielectric film 348 such as a silicon oxide film or a silicon nitridefilm. In an embodiment, the bottom electrode 346 is a conductor such astitanium nitride, titanium aluminum nitride, titanium nickel tin,tantalum nitride, tantalum silicon nitride, and others. The bottomelectrode 346 is depicted as making contact with the silicide contact344.

The bottom electrode 346 contacts the variable-resistance material 352.In an embodiment, variable-resistance material 352 is a phase-changematerial such as a chalcogenide material. The variable-resistancematerial 352 is contacted from above by a top electrode 354. A bit line356 is coupled to the top electrode 354.

FIG. 4 is a process flow 400 diagram for fabricating avariable-resistance material memory device according to an embodiment.The process flow 400 may illustrate fabrication technique embodimentsfor making the structures depicted in FIGS. 1, 2, and 3.

At 410, a hard mask and dielectric film are patterned above asemiconductive upper substrate that is disposed on a semiconductivelower substrate.

At 420, a first etch penetrates into the upper surface to form a firstrecess with a first recess bottom in the semiconductive upper substrate.

At 430, the process includes forming a first spacer that fills into thefirst recess but that leaves the first recess bottom uncovered after aspacer etch.

At 440, the process includes a second etch that penetrates deeper intothe semiconductive upper substrate.

At 450, the process includes forming a buried, self-aligned, silicideword line in the semiconductive upper substrate. In a non-limitingexample, the buried salicide word line is formed as depicted in FIGS.1e, 1f , and 1 g.

At 460, the process includes forming a diode in a recess in the hardmask that exposes previously protected semiconductive upper substratematerial In a non-limiting example, the diode is formed as illustratedin FIGS. 1h , and 1 j.

At 470, the process includes forming a bottom electrode above the diode.

At 472, the process includes forming a variable-resistance materialmemory above the bottom diode.

At 474, the process includes forming a top electrode above thevariable-resistance material memory.

In an embodiment, the epitaxial first film 140 fills the via 138 (FIG.1h ) and then is planarized by etchback or by polishing In anembodiment, a counter-doped second film 142 is formed by P+ implantationinto the surface of the epitaxial first film 140 by counter-doping.

FIGS. 5a to 5k show cross-section elevations of a semiconductor deviceduring processing according to an embodiment. In FIG. 5a , across-section elevation of a semiconductor device 500 is depicted duringprocessing. A semiconductive lower substrate 510 has been formed below asemiconductive upper substrate 512. In an embodiment, the semiconductivelower substrate 510 is P-doped in comparison to the semiconductive uppersubstrate 512 that is N+ doped.

A dielectric film 514 such as silicon dioxide is formed upon the uppersurface 516 of the semiconductive upper substrate 512. A first hard mask518 is disposed above the dielectric film 514, and the hard mask 518 andthe dielectric film 514 have been patterned to expose the upper surface516. In an embodiment, the first hard mask 518 is a nitride materiallike silicon nitride such as Si₃N₄.

FIG. 5b shows a cross-section elevation of the semiconductor devicedepicted in FIG. 5a after further processing according to an embodiment.The semiconductor device 501 has been etched through the upper surface516 (FIG. 1a ) to form a first recess 520 including a first recessbottom 522. The first hard mask 518 also exhibits a vertically exposedsurface 524 that facilitates a directional etch into the semiconductiveupper substrate 512.

FIG. 5c shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1b after further processing according to an embodiment.The semiconductor device 502 has been processed to form a first spacer526 on the first hard mask 518. The first spacer 526 has been formed byblanket deposition and a spacer etch. In an embodiment, the first spacer526 and the first hard mask 518 are nitride materials, and the spaceretch, although it is selective to etching nitride materials, removes thenitride material upon the first recess bottom 522 as well as upon thevertically exposed surfaces 524 of the first hard mask 518.Consequently, in an embodiment as depicted in FIG. 5c , the first hardmask 518 (FIG. 1b ) may be slightly height-reduced to become the firsthard mask 519.

FIG. 5d shows a cross-section elevation of the semiconductor devicedepicted in FIG. 5c after further processing according to an embodiment.The semiconductor device 503 has been etched through the first recessbottom 522 (FIG. 5 c) to form a second recess 528, a pillar 529 of someof the semiconductive upper substrate 512, and a second recess bottom530 in some of the semiconductive upper substrate 512. A second spacer556 is formed on the first spacer 526 and the first hard mask 519. In anembodiment, the second spacer 556 is a nitride material. In anembodiment the second spacer 556 is a nitride material that has adifferent composition than the first spacer 526 and the hard mask 519,both of which may also be nitride materials.

FIG. 5e shows a cross-section elevation of the semiconductor devicedepicted in FIG. 5d after further processing according to an embodiment.The semiconductor device 504 has been blanket isotropically oranisotropically etched such that an undercut 558 has formed below thefirst hard mask 519, the first spacer 526, and the second spacer 556.Accordingly, a pillar 529 has been formed of a part of thesemiconductive upper substrate 512.

Etching may be wet, such as an isotropic HNA etch, which includeshydrofluoric acid (HF), nitric acid (HNO₃), and acetic acid (CH₃OOH). Inan embodiment, an isotropic etch includes an ammonia fluoride-nitricacid (NH₄F/HNO₃) silicon etch. In an embodiment, an isotropic silicondry etch includes sulfur hexafluoride (SF₆). In an embodiment, anisotropic silicon dry etch includes xenon fluoride (XeF₂). In anembodiment, an anisotropic silicon wet etch includes potassium hydroxide(KOH) that can have a crystalline lattice etch ratio ((100):(111)) ofabout 400:1 In an embodiment, an anisotropic silicon wet etch includesammonium hydroxide (Na₄OH) that can have a crystalline lattice etchratio ((100):(111)) of about 8,000:1. In an embodiment, an anisotropicsilicon wet etch includes tetramethyl ammonium hydroxide (TMAH) that canhave a crystalline lattice etch ratio ((100):(111)) of about 10-35:1. Inan embodiment, an anisotropic silicon wet etch includes edp (EDP) thatcan have a crystalline lattice etch ratio ((100):(111)) of about 35:1.

FIG. 5f shows a cross-section elevation of the semiconductor devicedepicted in FIG. 5e after further processing according to an embodiment.The semiconductor device 505 has been processed under conditions tocause a buried oxide structure 560 to fill the undercut 558 (FIG. 5e )and to further isolate any two adjacent, spaced-apart pillars 529.

In a process embodiment, the buried oxide structure 560 is formed bythermal oxidation. In a process embodiment, the buried oxide structure560 is formed by spin-on dielectric (SOD) followed by an etchbackprocess. As illustrated, the buried oxide structure may have a bird'sbeak shape as seen in cross-section.

FIG. 5g shows a cross-section elevation of the semiconductor devicedepicted in FIG. 5e after further processing according to an embodiment.The semiconductor device 506 has been first processed to remove thesecond spacer 556 (FIG. 5f ). Next, the semiconductor device 506 hasbeen deposited with a first metal 532. The first metal 532 is used toform a silicide in the semiconductive upper substrate 512.

FIG. 5h shows a cross-section elevation of the semiconductor devicedepicted in FIG. 5g after further processing according to an embodiment.The semiconductor device 507 has been processed such that the firstmetal 532 has been reacted with the pillar 529 of the semiconductiveupper substrate 512 to form a salicidation 535 (self-alignedsilicidation) of the first metal 532. The salicidation melds into thesemiconductive upper substrate 512 including into the pillar 529. Aburied salicide word line 535 is formed by this process. In anembodiment, the first metal 532 is cobalt (Co), and the process hasallowed the salicide word line 535 to form as cobalt silicide (CoSi₂)material. After salicidation, any excess first metal 532 has beenremoved with a stripping procedure that is selective to leaving theburied salicide word line 535 as well as the first hard mask 519 and thefirst spacer 526. Because of the buried oxide layer 560, leakage betweenneighboring diodes, and leakage into the substrate (as seen in FIG. 5k )is significantly, if not completely, eliminated. Further, improvedcell-to-cell isolation is achieved by the elimination of lateral pnpbipolar junction transistor structures between adjacent word lines.

FIG. 5j shows a cross-section elevation of the semiconductor devicedepicted in FIG. 5h after further processing according to an embodiment.The semiconductor device 508 has been processed with an STI 536.Consequently, a given STI 536 completes isolation of neighboringsalicide word lines 535. The STI 536 may be processed by a blanketdeposition, followed by an etchback or a chemical-mechanical polishingthat stops on the first hard mask 519.

FIG. 5k shows a cross-section elevation of the semiconductor devicedepicted in FIG. 5j after further processing according to an embodiment.The semiconductor device 509 has been processed with a fourth etch thathas penetrated the first hard mask 519 and that exposes the pillar 529at a pillar upper surface 538. The fourth etch includes an etch recipethat is selective to leaving the semiconductive material of thesemiconductive upper substrate 512.

The semiconductor device 509 has also been processed by growing anepitaxial first film 540 upon the pillar 529 at the pillar upper surface538. In an embodiment where the pillar 529 is an N+ silicon, theepitaxial first film 540 is an N− silicon. In an embodiment, formationof the epitaxial first film 540 is carried out by in situ N− dopingduring epitaxial growth. In an embodiment, formation of the epitaxialfirst film 540 is carried out by epitaxial growth, followed by light N−doping thereof. In an embodiment, the epitaxial first film 540 fills avia that has been etched into the first hard mask 519. In an embodiment,a counter-doped second film 542 is formed by P+ implantation into thesurface of the epitaxial first film 540 by counter-doping.

After formation of the epitaxial first film 540 to form a diode 540,542. The diode 540, 542 is formed by growing a second film 542(epitaxial) above and on the epitaxial first film 540 according to anembodiment In an embodiment, the second film 542 (counter-doped) isformed by ion implantation of P+ materials into the upper surface of theepitaxial first film 540. In an embodiment where the epitaxial firstfilm 540 is an N− silicon, the second film 542 is a P+ silicon. In anembodiment, formation of the second film 542 is carried out by in situP+ doping during epitaxial growth. In an embodiment, formation of thesecond film 542 is carried out by epitaxial growth, followed by heavy P+doping thereof.

The semiconductor device 509 has also been processed to form a silicidecontact 544. After formation of the diode 540, 542, silicidation of aportion of the second film 542 is carried out. In an embodiment, acobalt film is deposited over the second film 542 and thermal conversionof a portion of the second film 542 is carried out. Consequently, thediode structure is altered and takes the form of the epitaxial firstfilm 540, an altered second film 542. Salicidation has formed thesilicide contact 544 above the second film 542.

Further processing includes the formation of a bottom electrode 546 in adielectric film 548 such as a silicon oxide film or a silicon nitridefilm. The bottom electrode 546 is depicted as making contact with thesilicide contact 544 and is illustrated as an open-ended cylinder. Othertypes of bottom electrodes may be formed as well such as a plug, aliner, and others. Accordingly, a buried salicide word line with aburied oxide semiconductor device 509 has been formed.

Further processing may be carried out to form a variable-resistancematerial memory such as the variable-resistance material memory 352depicted in FIG. 3. Consequently, a top electrode may also be formed tobe disposed above the variable-resistance material memory. In anembodiment, the variable-resistance material is any of the metalcombinations set forth in this disclosure In an embodiment, thevariable-resistance material may be any of the metal oxide combinationsset forth in this disclosure. In an embodiment, the variable-resistancematerial is any of the chalcogenide compounds set forth in thisdisclosure.

FIG. 6 shows a process flow 600 for fabricating the structures depictedin FIGS. 5a through 5k according to an embodiment.

At 610 a hard mask and dielectric film are patterned above asemiconductive upper substrate that is disposed on a semiconductivelower substrate.

At 620, a first etch penetrates into the upper surface to form a firstrecess with a first recess bottom in the semiconductive upper substrate.

At 630, the process includes forming a first spacer that fills into thefirst recess but that leaves the first recess bottom uncovered after aspacer etch.

At 640, the process includes a second etch that penetrates deeper intothe semiconductive upper substrate and forms a second spacer that fillsinto the recess.

At 650, the process includes forming an undercut in the semiconductiveupper substrate and forming a buried oxide layer that fills theundercut. The process also results in a more isolated pillar.

At 660, the process includes forming a buried, self-aligned, silicideword line in the semiconductive upper substrate. In a non-limitingexample, the buried salicide word line is formed as depicted in FIG. 5g.

At 670, the process includes forming a diode in a recess in the hardmask that exposes previously protected semiconductive upper substratematerial. In a non-limiting example, the diode is formed as illustratedin FIG. 5 k.

At 680, the process includes forming a bottom electrode above the diode.

At 682, the process includes forming a variable-resistance materialmemory above the bottom electrode.

At 684, the process includes forming a top electrode above thevariable-resistance material memory.

FIGS. 7a through 7f show cross-section elevations of a semiconductordevice during processing according to an embodiment. In FIG. 7a , across-section elevation of a semiconductor device 700 is depicted duringprocessing. A semiconductive lower substrate 710 has been formed below asemiconductive upper substrate 712. In an embodiment, the semiconductivelower substrate 710 is P− doped in comparison to the semiconductiveupper substrate 712 that is N+ doped.

A dielectric film 714 such as silicon dioxide is formed upon the uppersurface 716 of the semiconductive upper substrate 712. A first hard mask718 is disposed above the dielectric film 714, and the hard mask 718 andthe dielectric film 714 have been patterned to expose the upper surface716. In an embodiment, the first hard mask 718 is a nitride materiallike silicon nitride such as Si₃N₄.

FIG. 7b shows a cross-section elevation of the semiconductor devicedepicted in FIG. 7a after further processing according to an embodiment.The semiconductor device 701 has been etched through the upper surface716 (FIG. 7a ) to form a first recess 720 including a first recessbottom 722. The first hard mask 718 also exhibits a vertically exposedsurface 724 that facilitates a directional etch into the semiconductiveupper substrate 712.

FIG. 7c shows a cross-section elevation of the semiconductor devicedepicted in FIG. 7b after further processing according to an embodiment.The semiconductor device 702 has been processed to form a first spacer726 on the first hard mask 716. The first spacer 726 may be an adhesionfilm for a second spacer. A second spacer 756 is formed above theadhesion film 726. The first spacer 726 has been formed by blanketdeposition. In an embodiment, the first hard mask 718 is a nitridematerial, and the first spacer 726 is a refractory metal nitridecomposition such as a titanium nitride material. The spacer etch of thefirst spacer 726 and the second spacer 756 may remove some nitridematerial upon the vertically exposed surfaces 724 of the first hard mask718. Consequently, in an embodiment as depicted in FIG. 7c , the firsthard mask 718 (FIG. 7b ) may be slightly height-reduced to become thefirst hard mask 719.

FIG. 7c also show the formation of a metal second spacer 756 that isformed on the first spacer 726 and over the first hard mask 719. In anembodiment, the metal second spacer 756 is a refractory metal such astungsten. In an embodiment, the metal second spacer 756 is a refractorymetal such as tantalum. In an embodiment, the metal second spacer 756 isa refractory metal such as niobium.

FIG. 7d shows a cross-section elevation of the semiconductor devicedepicted in FIG. 7c after further processing according to an embodiment.The semiconductor device 703 has been etched through the first recessbottom 722 (FIG. 7c ) to form a second recess 728, a pillar 729 of someof the semiconductive upper substrate 712, and a second recess bottom730 in some of the semiconductive upper substrate 712.

FIG. 7e shows a cross-section elevation of the semiconductor devicedepicted in FIG. 7d after further processing according to an embodiment.The semiconductor device 704 has been processed with an STI 736.Consequently, a given STI 736 facilitates isolation of neighboring metalspacer word lines 756. The STI 736 may be processed by a blanketdeposition, followed by an etchback or a chemical-mechanical polishingthat stops on the first hard mask 719.

FIG. 7f shows a cross-section elevation of the semiconductor devicedepicted in FIG. 7e after further processing according to an embodiment.The semiconductor device 705 has been processed with a fourth etch thathas penetrated the first hard mask 719 and that exposed the pillar 729at a pillar upper surface 738. The fourth etch includes an etch recipethat is selective to leaving the semiconductive material of thesemiconductive upper substrate 712.

The semiconductor device 705 has also been processed by growing anepitaxial first film 740 upon the pillar 729 at the pillar upper surface738. In an embodiment where the pillar 729 is an N+ silicon, theepitaxial first film 740 is an N− silicon. In an embodiment, formationof the epitaxial first film 740 is carried out by in situ N− dopingduring epitaxial growth. In an embodiment, formation of the epitaxialfirst film 740 is carried out by epitaxial growth, followed by light N−doping thereof.

After formation of the epitaxial first film 740 to form a diode 740,742, the diode 740, 742 is formed by growing an second film 742 aboveand on the epitaxial first film 740. In an embodiment where theepitaxial first film 740 is an N− silicon, the second film 742 is a P+silicon. In an embodiment, formation of the second film 742 is carriedout by in situ P+ doping during epitaxial growth. In an embodiment,formation of the second film 742 is carried out by epitaxial growth,followed by heavy P+ doping thereof. In an embodiment, the second film742 is formed by P+ implantation of material into the upper surface ofthe epitaxial first film 740.

The semiconductor device 705 has also been processed to form a silicidecontact 744. After formation of the diode 740, 742, silicidation of aportion of the second film 742 is carried out. In an embodiment, acobalt film is deposited over the second film 742 and thermal conversionof a portion of the second film 742 is carried out. Consequently, thediode structure is altered and takes the form of the epitaxial firstfilm 740, an altered second film 742. Salicidation has formed thesilicide contact 744 above the second film 742.

Further processing includes the formation of a bottom electrode 746 in adielectric film 748 such as a silicon oxide film or a silicon nitridefilm. The bottom electrode 746 is depicted as making contact with thesilicide contact 744 and is illustrated as an open-ended cylinder. In anembodiment, the bottom electrode 746 may be a conductive plug, a liner,or other structure.

Further processing may be carried out to form a variable-resistancematerial memory such as the variable-resistance material memory 352depicted in FIG. 3. Consequently, a top electrode may also be formed tobe disposed above the variable-resistance material memory. In anembodiment, the variable-resistance material is any of the metalcombinations set forth in this disclosure. In an embodiment, thevariable-resistance material any of the metal oxide combinations setforth in this disclosure. In an embodiment, the variable-resistancematerial is any of the chalcogenide compounds set forth in thisdisclosure.

FIG. 8 is a shows a process flow 800 for fabricating the structuresdepicted in FIGS. 7a through 7k according to an embodiment.

At 810, a hard mask and dielectric film are patterned above asemiconductive upper substrate that is disposed on a semiconductivelower substrate.

At 820, a first etch penetrates into the upper surface to form a firstrecess with a first recess bottom in the semiconductive upper substrate.

At 830, the process includes forming a first and second spacer that fillinto the first recess but that leave the first recess bottom uncoveredafter spacer etching.

At 840, the process includes a second etch that penetrates deeper intothe semiconductive upper substrate.

At 850, the process includes forming a shallow trench isolationstructure.

At 860, the process includes forming a diode in a recess in the hardmask that exposes previously protected semiconductive upper substratematerial. In a non-limiting example, the diode is formed as illustratedin FIG. 7 e.

At 870, the process includes forming a bottom electrode above the diode.

At 872, the process includes forming a variable-resistance materialmemory above the bottom electrode.

At 874, the process includes forming a top electrode above thevariable-resistance material memory.

FIGS. 9a through 9f show cross-section elevations of a semiconductordevice during processing according to an embodiment. In FIG. 9a , across-section elevation of a semiconductor device 900 is depicted duringprocessing. A semiconductive lower substrate 910 has been formed below asemiconductive upper substrate 912. In an embodiment, the semiconductivelower substrate 910 is P− doped in comparison to the semiconductiveupper substrate 912 that is N+ doped.

A dielectric film 914 such as silicon dioxide is formed upon the uppersurface 916 of the semiconductive upper substrate 912. A first hard mask918 is disposed above the dielectric film 914, and the hard mask 918 andthe dielectric film 914 have been patterned to expose the upper surface916. In an embodiment, the first hard mask 918 is a nitride materiallike silicon nitride such as Si₃N₄.

FIG. 9b shows a cross-section elevation of the semiconductor devicedepicted in FIG. 9a after further processing according to an embodiment.The semiconductor device 901 has been etched through the upper surface916 (FIG. 9a ) to form a first recess 920 including a first recessbottom 922. The first hard mask 918 also exhibits a vertically exposedsurface 924 that facilitates a directional etch into the semiconductiveupper substrate 912. The semiconductor device 901 has been processed toform a temporary spacer 926 on the first hard mask 916. The temporaryspacer 926 has been formed by blanket deposition followed by a spaceretch. In an embodiment, the first hard mask 918 is a nitride material,and the temporary spacer 926 is also nitride material. The spacer etchof the temporary spacer 926 may remove some nitride material upon thevertically exposed surfaces 924 of the first hard mask 918. Consequentlyin an embodiment as depicted in FIG. 9c the first hard mask 918 (FIG. 9b) may be slightly height-reduced as the first hard mask 919.

FIG. 9c shows a cross-section elevation of the semiconductor devicedepicted in FIG. 9b after further processing according to an embodiment.The semiconductor device 902 has been etched through the first recessbottom 922 (FIG. 9b ) to form a second recess 928, a pillar 929 of someof the semiconductive upper substrate 912, and a second recess bottom930 in some of the semiconductive upper substrate 912.

FIG. 9d shows a cross-section elevation of the semiconductor devicedepicted in FIG. 9c after further processing according to an embodiment.The semiconductor device 903 shows the formation of a buried oxidestructure 960. In a process embodiment, the buried oxide structure 960is formed by thermal oxidation. In a process embodiment, the buriedoxide structure 960 is formed by SOD followed by an etchback process.

FIG. 9e shows a cross-section elevation of the semiconductor devicedepicted in FIG. 9d after further processing according to an embodiment.The temporary spacer has been removed. The semiconductor device 904shows a metal nitride first spacer 956 and a metal second spacer 962. Inan embodiment, the metal second spacer 962 is a refractory metal such astungsten. In an embodiment, the metal second spacer 962 is a refractorymetal such as tantalum. In an embodiment, the metal second spacer 962 isa refractory metal such as niobium.

The semiconductor device 904 has also been processed with an STI 936.Consequently, a given STI 936 facilitates isolation of neighboring metalspacer word lines 956. The STI 936 may be processed by a blanketdeposition, followed by an etchback or a chemical-mechanical polishingthat stops on the first hard mask 919.

FIG. 9f shows a cross-section elevation of the semiconductor devicedepicted in FIG. 9e after further processing according to an embodiment.The semiconductor device 905 has been processed with a fourth etch thathas penetrated the first hard mask 919 and that exposed the pillar 929at a pillar upper surface 938. The fourth etch includes an etch recipethat is selective to leaving the semiconductive material of thesemiconductive upper substrate 912.

The semiconductor device 905 has also been processed by growing anepitaxial first film 940 upon the pillar 929 at the pillar upper surface938. In an embodiment where the pillar 929 is an N+ silicon, theepitaxial first film 940 is an N− silicon. In an embodiment, formationof the epitaxial first film 940 is carried out by in situ N− dopingduring epitaxial growth. As in other embodiments, the epitaxial firstfilm may be etchback processed, followed by one of epitaxial growth orimplantation to form a diode. In an embodiment, formation of theepitaxial first film 940 is carried out by epitaxial growth, followed bylight N− doping thereof.

After formation of the epitaxial first film 940 to form a diode 940,942. The diode 940, 942 is formed by growing a second film 942 above andon the epitaxial first film 940 according to an embodiment. In anembodiment the second film 942 is formed by P+ implantation into theupper surface of the epitaxial first film 940. In an embodiment wherethe epitaxial first film 940 is an N− silicon, the second film 942 is aP+ silicon. In an embodiment, formation of the second film 942 iscarried out by in situ P− doping during epitaxial growth In anembodiment, formation of the second film 942 is carried out by epitaxialgrowth, followed by heavy P+ doping thereof.

The semiconductor device 905 has also been processed to form a silicidecontact 944. After formation of the diode 940, 942, silicidation of aportion of the second film 942 is carried out. In an embodiment, acobalt film is deposited over the second film 942 and thermal conversionof a portion of the second film 942 is carried out. Consequently, thediode structure is altered and takes the form of the epitaxial firstfilm 940 and an altered second film 942. Salicidation has formed thesilicide contact 944 above the second film 942.

Further processing includes the formation of a bottom electrode 946 in adielectric film 948 such as a silicon oxide film or a nitride film. Thebottom electrode 946 is depicted as making contact with the silicidecontact 944 and is illustrated as an open-ended cylinder. Other types ofbottom electrodes can be implemented such as plug bottom electrodes,liner electrodes, and others.

Further processing may be carried out to form a variable-resistancematerial memory such as the variable-resistance material memory 352depicted in FIG. 3. Consequently, a top electrode may also be formed tobe disposed above the variable-resistance material memory. In anembodiment, the variable-resistance material is any of the metalcombinations set forth in this disclosure. In an embodiment, thevariable-resistance material is any of the metal oxide combinations setforth in this disclosure. In an embodiment, the variable-resistancematerial is any of the chalcogenide compounds set forth in thisdisclosure.

FIG. 10 is a shows a process flow 1000 for fabricating the structuresdepicted in FIGS. 9a through 9f according to an embodiment.

At 1010, a hard mask and dielectric film are patterned above asemiconductive upper substrate that is disposed on a semiconductivelower substrate.

At 1020, a first etch penetrates into the upper surface to form a firstrecess with a first recess bottom in the semiconductive upper substrate.

At 1030, the process includes forming a first spacer that fills into thefirst recess but that leaves the first recess bottom uncovered afterspacer etching.

At 1040, the process includes a second etch that penetrates both thesemiconductive upper substrate and the semiconductive lower substrate.

At 1050, the process includes forming a buried oxide structure, followedby removal of the nitride temporary spacer.

At 1060, the process includes forming a nitride first spacer, a metalsecond spacer, and a shallow trench isolation above the buried oxide.

At 1070, the process includes forming a diode in a recess in the hardmask that exposes previously protected semiconductive upper substratematerial. In a non-limiting example, the diode is formed as illustratedin FIG. 9 f.

At 1072, the process includes forming a bottom electrode above thediode.

At 1074, the process includes forming a variable-resistance materialmemory above the bottom electrode.

At 1076, the process includes forming a top electrode above thevariable-resistance material memory.

FIG. 11 illustrates an electronic device 1100 that includes buried wordline structures in connection with the variable-resistance materialmemory embodiments as described above. The electronic device 1100includes a first component 1120 that benefits from variable-resistancematerial memory embodiments. Examples of first component 1120 includedynamic random-access memory arrays. In an embodiment, the firstcomponent 1120 is a processor that includes variable resistance materialmemory arrays that are used for booting up the processor. In theseexamples, device operation is improved with the presence ofvariable-resistance material memory embodiments.

In an embodiment, the device 1100 further includes a power source 1130.The power source 1130 is electrically connected to the first devicecomponent 1120 using interconnecting circuitry 1140. In an embodiment,the interconnecting circuitry 1140 includes variable-resistance materialmemory embodiments using processing methods described above. In additionto depositing material as described above, techniques such aslithography with masks and/or etching etc. can be used to patternconducting circuitry.

In an embodiment, the device 1100 further includes a second devicecomponent 1110. The second device component 1110 is electricallyconnected to the first component 1120 using interconnecting circuitry1142. Likewise, in one embodiment, the interconnecting circuitry 1142includes variable-resistance material memory embodiments that are formedusing methods described above. Examples of second device components 1110include signal amplifiers, flash memory, logic circuitry, or othermicroprocessing circuits, etc. Aside from interconnecting circuitry, inan embodiment, the first device component 1120 and/or the second devicecomponent 1110 include variable-resistance material memory embodimentsusing methods described above.

FIG. 12 shows one specific example of a computer system includingvariable-resistance material memorys formed as described above. Thecomputer system 1200 contains a processor 1210 and a memory system 1212housed in a computer unit 1215. The computer system 1200 is but oneexample of an electronic system containing another electronic system. Inan embodiment, the computer system 1200 contains an input/output (I/O)circuit 1220 that is coupled to the processor 1210 and the memory system1212. In an embodiment, the computer system 1200 contains user interfacecomponents that are coupled to the I/O circuit 1220. In an embodiment, avariable-resistance material memory embodiment is coupled to one of aplurality of I/O pads or pins 1230 of the 1/O circuit 1220. The I/Ocircuit 1220 can then be coupled to at least one of a monitor 1240, aprinter 1250, a bulk storage device 1260, a keyboard 1270, and apointing device 1280. It will be appreciated that other components areoften associated with the computer system 1200 such as modems, devicedriver cards, additional storage devices, etc. It will further beappreciated that the processor 1210, the memory system 1212, the I/Ocircuit 1220, and partially isolated structures or data storage devicesof computer system 1200 can be incorporated on a single integratedcircuit. Such single package processing units may reduce thecommunication time between the processor 1210 and the memory system1200.

This Detailed Description refers to the accompanying drawings that show,by way of illustration, specific aspects and embodiments in which thepresent disclosure may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosed embodiments. Other embodiments may be used and structural,logical, and electrical changes may be made without departing from thescope of the present disclosure. The various embodiments are notnecessarily mutually exclusive, as some embodiments can be combined withone or more other embodiments to form new embodiments.

The Detailed Description is, therefore, not to be taken in a limitingsense, and the scope of this disclosure is defined only by the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

The terms “wafer” and “substrate” used in the description include anystructure having an exposed surface with which to form an electronicdevice or device component such as a component of an integrated circuit(IC). The term substrate is understood to include semiconductor wafers.The term substrate is also used to refer to semiconductor structuresduring processing and may include other layers such assilicon-on-insulator (SOI). etc. that have been fabricated thereupon.Both wafer and substrate include doped and undoped semiconductors,epitaxial semiconductor layers supported by a base semiconductor orinsulator, as well as other semiconductor structures well known to oneskilled in the art.

The term conductor is understood to include semiconductors and the terminsulator or dielectric is defined to include any material that is lesselectrically conductive than the materials referred to as conductors.

The term “horizontal” as used in this application is defined as a planeparallel to the conventional plane or surface of a wafer or substrate,regardless of the orientation of the wafer or substrate. The term“vertical” refers to a direction perpendicular to the horizontal asdefined above. Prepositions, such as “on,” “side” (as in “sidewall”),“higher,” “lower.” “over,” and “under” are defined with respect to theconventional plane or surface being on the top surface of the wafer orsubstrate, regardless of the orientation of the wafer or substrate.

The Abstract is provided to comply with 37 C.F.R. §1.72(b), requiring anabstract that will allow the reader to quickly ascertain the nature ofthe technical disclosure. It is submitted with the understanding that itwill not be used to interpret or limit the scope or meaning of theclaims. In addition, in the foregoing Detailed Description, variousfeatures may be grouped together to streamline the disclosure. Thismethod of disclosure is not to be interpreted as reflecting an intentionthat the claimed embodiments require more features than are expresslyrecited in each claim. Rather, as the following claims reflect,inventive subject matter may lie in less than all features of a singledisclosed embodiment. Thus the following claims are hereby incorporatedinto the Detailed Description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. A process of forming a memory structure,comprising: forming a first recess in an upper semiconductive substrateby use of a hard mask, wherein the upper semiconductive substrate isdisposed above a lower semiconductive substrate; forming a temporaryspacer in the first recess; forming a second recess that penetrates intothe lower semiconductive substrate, and that forms a pillar in the uppersemiconductive substrate; forming a buried oxide in the lowersemiconductive substrate and in the pillar; removing the temporaryspacer; forming a nitride first spacer on the pillar; forming a metalsecond spacer on the nitride spacer; forming a shallow trench isolationadjacent the pillar; forming a diode in a recess of the hard mask thatexposes the pillar at an upper surface thereof; and forming avariable-resistance material coupled to the diode.
 2. The process ofclaim 1, wherein forming the diode in the recess of the hard mask thatexposes the pillar at the upper surface thereof includes: etching therecess in the hard mask; forming an epitaxial first film above and onthe pillar at the upper surface; and forming a second film above and onthe epitaxial first film.
 3. The process of claim 1, wherein forming thevariable-resistance material that is coupled to the diode includes:siliciding a portion of the epitaxial second layer to form a silicidecontact; forming a bottom electrode on the silicide contact; forming thevariable-resistance material on the bottom electrode; and forming a topelectrode on the variable-resistance material.
 4. The process of claim1, wherein the variable resistance material is selected from an alloy, aquasi-metal composition, a metal oxide, and a chalcogenide.
 5. Theprocess of claim 1, wherein the variable resistance material includes aphase-change material.
 6. The process of claim 1, wherein the variableresistance material includes one or more of a gallium-containingmaterial, a germanium-containing material, an indium-containingmaterial, an antimony-containing material, a tellurium-containingmaterial, a selenium-containing material, an arsenic-containingmaterial, an aluminum-containing material, a tin-containing material, apalladium-containing material, a silver-containing material, or acolossal magneto-resistive film.
 7. The process of claim 1, wherein thevariable-resistance material includes a doped chalcogenide glass of thegeneral formula A_(x)B_(y), B selected from sulfur, selenium, andtellurium, and mixtures thereof, and A includes at least one elementfrom Group III-A, Group IV-A, Group V-A, or Group VII-A of the periodictable.
 8. The process of claim 1, wherein the silicide contact includescobalt silicide.
 9. The process of claim 1, wherein a silicide contactis formed in direct contact with the diode.
 10. A process of forming amemory structure, comprising: forming a first recess in an uppersemiconductive substrate by use of a hard mask, the upper semiconductivesubstrate disposed above a lower semiconductive substrate; forming asecond recess that at least penetrates into the upper semiconductivesubstrate, and that forms a pillar in the upper semiconductivesubstrate; forming a buried salicide word line in the pillar; forming adiode in a recess of the hard mask that exposes the pillar at an uppersurface thereof; and forming a variable-resistance material coupled tothe diode.
 11. The process of claim 10, wherein forming the buriedsalicide word line in the pillar includes: forming a metal over thepillar and in the second recess; and heating the metal to form theburied salicide in the pillar.
 12. The process of claim 10, whereinforming the diode in the recess of the hard mask that exposes the pillarat the upper surface thereof includes: etching the hard mask to form therecess in the hard mask; forming an epitaxial first film above and onthe pillar at the upper surface; and forming an epitaxial second filmabove and on the epitaxial first film.
 13. The process of claim 12,wherein forming the variable-resistance material that is coupled to thediode includes: siliciding a portion of the epitaxial second film toform a silicide contact; forming a bottom electrode on the silicidecontact; forming the variable-resistance material on the bottomelectrode; and forming a top electrode on the variable-resistancematerial.
 14. The process of claim 10, wherein forming the diode in therecess of the hard mask that exposes the pillar at the upper surfacethereof includes: etching the hard mask to form the recess in the hardmask; forming an epitaxial first film above and on the pillar at theupper surface; and forming a second film above and on the epitaxialfirst film.
 15. The process of claim 14, wherein forming thevariable-resistance material that is coupled to the diode includes:siliciding a portion of the second film to form a silicide contact,forming a bottom electrode on the silicide contact; forming thevariable-resistance material on the bottom electrode; and forming a topelectrode on the variable-resistance material.
 16. The process of claim10, wherein the salicide word line includes cobalt silicide.
 17. Amemory structure, comprising: an upper semiconductive substrate disposedabove a lower semiconductive substrate, wherein the upper semiconductivesubstrate includes a pillar that is isolated by a shallow trenchisolation structure; an epitaxial first film disposed on an uppersurface of the pillar; an epitaxial second film disposed above and onthe epitaxial first film, wherein the epitaxial first film and theepitaxial second film form a diode; a variable resistance materialcoupled to the diode; and a salicide word line having at least a portiondisposed below the epitaxial first film and in the upper semiconductivesubstrate above the lower semiconductive substrate, the salicide wordline having an outer surface coplanar with an outer surface of the uppersemiconductor substrate, and a top surface of the upper semiconductorsubstrate being above a top surface of the salicide word line.
 18. Theapparatus of claim 17, further comprising a spacer disposed above thesalicide word line.
 19. The apparatus of claim 17, further comprising aburied oxide layer that fills an undercut in the pillar.
 20. Theapparatus of claim 17, further comprising: a spacer disposed above thesalicide word line; and a buried oxide layer that fills an undercut inthe pillar.